The present invention concerns an apparatus for bending sheet metal pieces or sheet metal strips into a trapeze-like shape or other shapes useful in industrial applications.
An apparatus of the type of concern is shown in DE 198 02 589 A1 and WO 99/37471. This known apparatus, designed to perform bending operations, is comprised of dies and attached to them upper-side pressure cylinders moveable horizontally in the machine positioned before and after the lower-side pressure cylinder with its corresponding press punch in order to ensure tension-free length reduction in the sheet metal piece during the bending operation. It has been found that the horizontal sliding arrangement of the dies and their corresponding pressure cylinders leads to a more complicated and costly design of the apparatus. Another problem with this known apparatus for stepwise bending is its relatively low speed of operation.
An objective of the present invention is the provision of an apparatus, of the type mentioned above, that is simpler, and, therefore, its development is less costly and more economical. Additionally, this apparatus should operate at higher speed.
This objective is achieved by an apparatus, satisfying characteristics of the principal concepts recited in the patent claim 1, is developed.
Further development and improvements of the invention are subject of subsequent claims of this patent.
The use of the vice plates, which move in the horizontal direction and function to secure in place sheet metal pieces for bending operation, make it possible to provide the apparatus with a very robust design. Additionally, when needed, replacement of the moveable vice plates is economical.
This design makes it possible to increase the speed of the stepwise process when the strip material is bent, as well as the process throughput, approximately 10 times.
According to the invention, adjustment cylinders serve primarily to return the vice plates, after each step of the bending process, back to their initial horizontal position. When the adjustment cylinders are designed with dual-side action, they can be used at least to sustain horizontal movements caused by the bending process.
In cases where the dies of the bending apparatus can move independently in the vertical direction, the apparatus can be utilized for multiple purposes because it can bend different shapes, e.g., trapeze-like shapes, and it is simpler to remove the trapeze-like section from the apparatus, especially, if the shape of the bent section is asymmetric.